Polymerization process using metal pyrophosphate hydrate-bf3 catalyst



POLYMERIZATION PRQCESS USING METAL PYROPHOSPHATE HYDRATE-BF CATALYST No Drawing. Qriginal application April 24, 1956, Serial No. 580,256. Divided and this application March 18, 1957, Serial No. 646,833

2 Claims. (Cl. 260-943) This invention relates to a process for polymerizing ethylene, and is a division of application Serial No. 580; 256, filed April 24, 1956, and now abandoned.

Commercial grade anhydrous boron trifluoride may be utilized as one member of the catalyst pair.

The other member of the catalyst pair, hereinafter spoken of as the solid member, is a metal pyrophosphate hydrate, i.e., a metal pyrophosphate salt containing Water of hydration. The salt may be used as a fine powder, as pellets, or may be supported on a solid carrier such as alumina, charcoal, silica gel, etc. Not all metal pyrophosphates which contain water of hydration are suitable, nor are all metal ions suitable. The particular metal ion component of the pyrophosphate salt hydrates is aluminum, beryllium, cadmium, cobaltous, cuprous, ferrous, ferric, manganous, nickelous, stannic, thorium, titanium, zinc and zirconium.

It is necessary that the above-defined metal pyrophosphate salts contain hydrate water. The anhydrous salts do not have any promotional effect on, the activity of BF In those cases wherein a salt may exist in forms having various amounts of water of hydration present, it is not necessary that any particular hydrate be used. Apparently it is necessary only that some Water-of hydration be present.

The BF and the defined salt react to form a solid material containing complexed BF When the salt hydrate and BF are contacted in a closed vessel, the BF partial pressure drops very rapidly at first and then gradually approaches a constant value. It appears that a very rapid reaction between the BE, and some of the water of hydration takes place. This initially rapid reaction is then followed by a relatively slow reaction between the re maining molecules of hydrate Water and additional BF In the case of ferric pyrophosphate containing 11 moles of hydrate water per mole of the salt, it appears that 4 or 5 moles of hydrate water are rapidly reacted. However, stirring of finely powdered hydrate salt in the presence of excess BF at about room temperature for a period of about 20 hours, results in the reaction of 1 mole of BF for each mole of hydrate water present in the ferric pyrophosphate hydrate. It appears that when the salt hydrate is exposed to BF even in the presence of hydrocarbon reactants, eventually all of the water of hydration will become associated with BF on about a 1 mole of BF per mole of hydrate Water basis.-

In general, the process is carried out utilizing an amount of BF;, which is in excess of that required to complex with all the hydrate water present in the contacting zone, namely, in excess of about 1 mole of BF per mole of hydrate water present in the defined salt. It is preferred to complex all the water of hydration; i.e., have the complex contain about 1 mole of BF 'per mole of hydrate water present; and have free-BF} present in a weight ratio of BF to ethylene of between about 0.2 and 1.5

The contacting of the ethylene in the presence of the defined catalyst pair is continued until an appreciable amount of ethylene polymer has been produced.

Patent 0 It hasbeen pointed out that the solid. member of the catalyst pair is really a complex of the metal pyrophosphate-salt hydrate and BF the BF apparently reacting with the water of hydration. The complex may be preformed, by exposing the salt hydrate to BE, for a time sufiicient to introduce some BF into the solid component or even enough to complex all of the water of hydration; this being done before the reactants are introduced into the reaction zone or even before the solid member of the catalyst pair is positioned in the reaction zone. The complex may be formed in situ during a batch-type reaction. In the batch-type operation, it is convenient to introduce all the BE, into the reaction vessel at once. This amount of BF 3 is sulficient not only to complex with the water of hydration but also provide the desired amount of free- BFg. In a flow system, the solid member may be prepared in situ by charging fresh hydrate salt to the reaction zone and forming the complex during the initial passage of reactants and BE, over the salt hydrate.

The process may be carried out at a temperature between about -20 C. and C.; atmospheric tempera- 7 In this run, ferric pyrophosphate .9H O and BF was used as the catalyst pair in a run charging only ethylene as the hydrocarbon.

A 1.4 liter bomb was charged with 50 grams of ferric pyrophosphate .9H O and 505 grams of Cl. n-hexane. The bomb was rocked while 56 grams of BF were pressured in slowly. The rocking was continued until the BF pressure had become constant. Over a period of 3 hours, grams of ethylene were added to the bomb. A sample of the material was withdrawn for Pody analysis. The nhexane 'Was stripped from the remainder of the product which was a tacky viscous mass. The hydrate salt was recovered with a dark coating. The coated salt was extracted in a Soxhlet extractor for 8 hours using hot benzene. The benzene was distilled away to recover the dissolved material. The conditions and yields of this run are set out in Table I. This run shows that this salt hydrate and BF catalyst pair is effective in producing high molecular weight ethylene polymer.

Table I.Ethylene polymerization using ferric pyrophosphate plus BF Run N o 27 Temperature C.) 13-34 Time (Hours) Pressure (p.s.i.g.) -300 BF3/C2= (Wt) 0. 4 Yields:

Ethylene Added m 170 Ethylene Reacting (Pody Data) gm. 116 C Soluble Polymer:

Yield from Pody Data gm 54 Actual Polymer Recovered gm. 1 66 C Insoluble Polymer:

Actual Polymer Recovered grn 2 12 Total Polymer Recovered gm 78 1 Bromine N o. 43 Iodine No. 64, MAV 6.6. 9 MAV 16.0 (MAV=Maleic Anhydride Value).

We claim:

1. An ethylene polymerization process which comprises contacting ethylene at a temperature between about -20 C. and 100 C. in the presence of liquid hexane solvent for a time sufiicient to produce an appreciable amount of ethylene polymer in the presence of a catalyst comprising essentially (i) a ferric pyrophosphate salt containing water of hydration, and (ii) boron trifluoride, said BF being present in an amount in excess of one mole per mole of hydrate water present in said salt, and re- 9,924,595 I v 3 a a 4 a covering ethylene polymer from product hydrocarbon References Cited in the file of this patent mixture obtained from said contacting zone.

2. The process of claim 1 wherein the BF is present UNITED STATES PATENTS in an amount of about 1 mole per mole of hydrate water 2,183,503 McAlevy Dec. 12, 1939 present in said salt and free-BF is present in a weight 5 2,416,106 Linn et a1 Feb. 18, 1947 ratio of BF to ethylene of between about 0.2 and 1.5. 2,748,090 Watkins May 29, 1956 

1. AN ETHYLENE POLYMERIZATION PROCESS WHICH COMPRISES CONTACTING ETHYLENE AT A TEMPERATURE BETWEEN ABOUT -20*C. AND 100*C. IN THE PRESENCE OF LIQUID HEXANE SOLVENT FOR A TIME SUFFICIENT TO PRODUCE AN APPRECIABLE AMOUNT OF ETHYLENE POLYMER IN THE PRESENCE OF A CATALYST COMPRISING ESSENTIALLY (I) A FERRIC PYROPHOSPHATE SALT CONTAINING WATER OF HYDRATION, AND (II) BORON TRIFLUORIDE, SAID BF3 BEING PRESENT IN AN AMOUNT IN EXCESS OF ONE MOLE, PER MOLE OF HYDRATE WATER PRESENT IN SAID SALT, AND RECOVERING ETHYLENE POLYMER FROM PRODUCT HYDROCARBON MIXTURE OBTAINED FROM SAID CONTACTING ZONE. 